1,720,979 research outputs found
The transcription activation function of C/EBPalpha is required for induction of granulocytic differentiation
No full textThe CCAAT/enhancer binding protein-a. (C/EBPalpha) is a transcription factor required for differentiation of myeloid progenitors. In addition to specific DNA binding, C/EBPa is also involved in protein-protein interactions, some of which (p21, Cdk2/Cdk4, E2F) appear to be required for inhibition of proliferation and possibly differentiation. To investigate the mechanisms of C/EBPalpha-induced granulocytic differentiation, we generated C/EBPalpha mutants reportedly defective in DNA binding, transactivation, and Cdk2/Cdk4 and E2F interaction and assessed their effects in a myeloid precursor cell line, primary bone marrow and C/EBPalpha knockout fetal liver precursor cells. We show here that the DNA binding-deficient Lys298Glu mutant, the E2F binding-deficient basic region mutant 2 (BRM-2) carrying the IIe294AIa and Arg 47AIa substitutions, and the transactivation-deficient N-terminus truncated p30 mutant all fall to promote differentiation on ectopic expression in myeloid precursor cells. By contrast, ectopic expression of the Cdk2/ Cdk4 interaction-deficient Delta177-191 mutant promotes differentiation and induces gene expression as effectively as wildtype C/EBPa. Thus, the integrity of the transactivation and DNA binding domains, but not of the Cdk2/Cdk4 interaction region, is necessary for C/EBPalpha-induced differentiation. Since the E2F binding-deficient BRM-2 mutant interacted with E2F-1 but failed to activate gene expression, our results lend support to the hypothesis that activation of gene transcription is the determining factor in C/EBPalpha-dependent differentiation
Resistance to apoptosis in CTLL-2 cells overexpressing B-Myb is associated with B-Myb-dependent bcl-2 induction
No full textTranscriptional regulators of the Myb family play important roles in cell proliferation, differentiation, and survival. To investigate the role of Myb proteins in the regulation of apoptosis, we studied the apoptotic response of interleukin 2-dependent CTLL-2 cells stably transfected with B-Myb. B-Myb-overexpressing cells showed a diminished cytokine dependence and were resistant to apoptosis induced by doxorubicin, ceramide, and dexamethasone, Overexpression of B-Myb was associated with enhanced expression of bcl-2, which was dependent, at least in part, on increased transcription. In transient transfection assays in T-lymphoblastic cells, B-Myb was able to stimulate the promoter activity of the bcl-2 5' flanking region linked to the chloramphenicol acetyltransferase reporter gene. A segment of the bcl-2 promoter (nucleotides +34 to +58 relative to the transcription initiation site) contained a putative Myb-binding site and was shown to specifically interact with B-Myb and to confer B-Myb responsiveness to a bcl-2/chloramphenicol acetyltransferase reporter construct. These results indicate that B-Myb promotes T cells survival by enhancing the expression of bcl-2 and identify bcl-2 as a B-Myb target gene regulated in a DNA binding-dependent manner
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Resistance to apoptosis in CTLL-2 cells constitutively expressing c-Myb is associated with induction of bcl-2 expression and Myb-dependent regulation of bcl-2 promoter activity
No full textc-Myb, the cellular homologue of the transforming gene of the avian myeloblastosis virus, is preferentially expressed in all hematopoietic lineages, including T and B lymphocyte lineages, In T lymphocytes, c-Myb expression appears to be required for cell cycle progression and proliferation, To further investigate the role of c-Myb in T cell proliferation and survival, interleukin (IL) 2-dependent CTLL-2 cells were transfected with a constitutively active c-myb or with a c-myb antisense construct able to down-regulate endogenous Myb levels, and the transfectants were assessed for proliferation and survival in low concentrations of IL-2 and for susceptibility to dexamethasone-induced apoptosis, Compared with control cells, CTLL-2 cells constitutively expressing c-Myb proliferate in low concentrations of IL-2 and are less susceptible to apoptosis induced bq IL-2 deprivation or treatment with dexamethasone. In contrast, cells transfected with an antisense c-myb construct do not proliferate in Low concentrations of IL-2 and undergo apoptosis upon IL-2 deprivation or dexamethasone treatment more rapidly than parental cells, Overexpression of c-Myb was accompanied by up-regulation of BCL-2 expression, In transient transfection assays, the murine bcl-2 promoter was efficiently transactivated by c-Myb, but such effect was observed also in cells transfected with a DNA binding-deficient c-myb construct, Moreover, in gel retardation assays, a 38-bp oligomer in the shortest bcl-2 promoter segment regulated by c-Myb formed a specific complex with nuclear extracts from c-Myb transfected CTLL-2 cells, Thus, these results strongly suggest that c-Myb? in addition to regulating T cell proliferation, protects T lymphocytes from apoptosis by induction of BCL-2 expression, which involves a c-Myb-dependent mechanism of promoter regulation
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